slirp: avoid IN6_IS_ADDR_UNSPECIFIED(), rather use in6_zero()

Host: Mac OS 10.12.5
Compiler: Apple LLVM version 8.1.0 (clang-802.0.42)

  slirp/ip6_icmp.c:80:38: warning: taking address of packed member 'ip_src' of class or
        structure 'ip6' may result in an unaligned pointer value
        [-Waddress-of-packed-member]
              IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)) {
                                       ^~~~~~~~~~
  /usr/include/netinet6/in6.h:238:42: note: expanded from macro 'IN6_IS_ADDR_UNSPECIFIED'
          ((*(const __uint32_t *)(const void *)(&(a)->s6_addr[0]) == 0) && \
                                                  ^
Reported-by: NJohn Arbuckle <programmingkidx@gmail.com>
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>

slirp/ip6_icmp.c

@@ -77,7 +77,7 @@ void icmp6_send_error(struct mbuf *m, uint8_t type, uint8_t code)
     DEBUG_ARGS((dfd, " type = %d, code = %d\n", type, code));
 
     if (IN6_IS_ADDR_MULTICAST(&ip->ip_src) ||
-            IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)) {
+            in6_zero(&ip->ip_src)) {
         /* TODO icmp error? */
         return;
     }
@@ -272,7 +272,7 @@ static void ndp_send_na(Slirp *slirp, struct ip6 *ip, struct icmp6 *icmp)
     struct mbuf *t = m_get(slirp);
     struct ip6 *rip = mtod(t, struct ip6 *);
     rip->ip_src = icmp->icmp6_nns.target;
-    if (IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)) {
+    if (in6_zero(&ip->ip_src)) {
         rip->ip_dst = (struct in6_addr)ALLNODES_MULTICAST;
     } else {
         rip->ip_dst = ip->ip_src;
@@ -350,7 +350,7 @@ static void ndp_input(struct mbuf *m, Slirp *slirp, struct ip6 *ip,
                 && icmp->icmp6_code == 0
                 && !IN6_IS_ADDR_MULTICAST(&icmp->icmp6_nns.target)
                 && ntohs(ip->ip_pl) >= ICMP6_NDP_NS_MINLEN
-                && (!IN6_IS_ADDR_UNSPECIFIED(&ip->ip_src)
+                && (!in6_zero(&ip->ip_src)
                     || in6_solicitednode_multicast(&ip->ip_dst))) {
             if (in6_equal_host(&icmp->icmp6_nns.target)) {
                 /* Gratuitous NDP */

slirp/ndp_table.c

@@ -23,7 +23,7 @@ void ndp_table_add(Slirp *slirp, struct in6_addr ip_addr,
                 ethaddr[0], ethaddr[1], ethaddr[2],
                 ethaddr[3], ethaddr[4], ethaddr[5]));
 
-    if (IN6_IS_ADDR_MULTICAST(&ip_addr) || IN6_IS_ADDR_UNSPECIFIED(&ip_addr)) {
+    if (IN6_IS_ADDR_MULTICAST(&ip_addr) || in6_zero(&ip_addr)) {
         /* Do not register multicast or unspecified addresses */
         DEBUG_CALL(" abort: do not register multicast or unspecified address");
         return;
@@ -60,7 +60,7 @@ bool ndp_table_search(Slirp *slirp, struct in6_addr ip_addr,
     DEBUG_ARG("ip = %s", addrstr);
 #endif
 
-    assert(!IN6_IS_ADDR_UNSPECIFIED(&ip_addr));
+    assert(!in6_zero(&ip_addr));
 
     /* Multicast address: fec0::abcd:efgh/8 -> 33:33:ab:cd:ef:gh */
     if (IN6_IS_ADDR_MULTICAST(&ip_addr)) {